The invention relates to a positive displacement pump, in particular a reciprocating-armature or solenoid positive displacement pump, with a pump head, in which at least one pump space is provided, with a pump diaphragm, which is associated with the at least one pump space and which separates the pump space from a reciprocating drive, and with a reciprocating drive, which has a magnetic armature, which is guided movably in the longitudinal direction and which acts on a flat side of the pump diaphragm which is remote from the pump space and which can be caused to perform an intake stroke electromagnetically counter to a restoring force by means of a coil.
Positive displacement pumps of the type mentioned at the outset configured as reciprocating-armature pumps which have a pump head, in which at least one pump space is provided which can have a spherical dome shape, for example, are already known. A pump diaphragm which separates the pump space from a reciprocating drive is associated with the at least one pump space. The reciprocating drive has a magnetic armature, which is guided in the longitudinal direction and which acts on that flat side of the diaphragm which is remote from the pump space and can be caused to perform an intake stroke counter to a restoring force by means of an electromagnet.
If the abovementioned reciprocating-armature pump is operating in the delivery mode, a compression spring has the task of implementing the pressure stroke. The intake stroke is implemented by the force which is built up in the magnetic circuit by the coil of the electromagnet. It is critical here that the magnetic circuit built up by the electromagnet is guided as optimally as possible through the magnetically conductive components of the pump and is transferred to the magnetic armature imparting the pump movement.